CG5 declination motor just stopped working!

I have a Celestron C8 on a CG5 Advanced Series Go-To mount. It has been working wonderfully for me for three years now, especially after a DIY Hypertune two years ago.

Last night I was at a star party for the ALCon2012 convention. My second star party this week. My mount worked perfectly fine at the Wednesday night star party and was working fine the first half of last night's star party.

At one point, someone asked if I could slew to the moon since it had finally just cleared the trees on the horizon. I punched the command into my scope and off it went. Except it was widely off track. The RA axis was moving as it should, but the DEC axis not moving at all. I tried slewing to a different object, and the same thing happened. RA motor would slew and track but the DEC motor wouldn't move a millimeter. After the scope would come to a stop after slewing in the RA, it would just sit there. The hand controller still had the spinning thing in the display indicating that it was still trying to slew even though it wasn't moving anymore.

I turned off my mount and moved back to the index marks. Started the mount back up and tried to perform a two-star alignment. No go. The RA would move but not the DEC. I unplugged and replugged in the DEC cable from both ends and tried again. No go. I repeated this cycle a couple more times to no avail.

Eventually, I grew tired of messing with it and decided to just start hand-pointing my scope to targets and letting the RA axis continue its tracking. It made for a VERY slow rest of the night at the star party. Star hopping with an inoperable CG5 mount is tedious and slow!

So, anyone have any ideas what may be causing my issue? Is my DEC motor burned out? Is there loose connections in the DEC port? Bad DEC cable? I won't have any time to pull it apart and start looking at it for a few days. So I'm hoping to get some ideas from y'all in the meantime. Thanks!

I would try the dec. board first, then cabling, then look at the motor itself. All the parts are available through the support section spare parts shop. It is possible for the wires from the dec motor to the dec board can become "unstuffed" and pinch during movement. I had to tape mine down.

Did you get a No Response Error 17? Typically, you will get this error if the cable or motor control board is bad. It means the hand controller can't talk to the declination motor control board. If you didn't get this error, I'd be looking elsewhere, like the motor itself or, as the previous poster suggested, the wiring from the board to the motor.

And by "not move," do you mean you can't hear the motor running at all, or just that the scope is not moving?

You should check the connections of the Dec motor first. Make sure that the Dec cable is full seated in the sockets at both ends. You should also look into the sockets and insure that the wire contacts are clean and properly aligned. If you have the capabilities, check the Dec cable for continuity. The RJ12 connectors are known to have connection issues. If you have the crimping tool or know someone that does, try re-crimping or replacing the connectors. The next thing you will want to check is the connections from the MC board to the power board and the connection from the Dec board in the Dec cover to the motor. You can swap the Dec and RA motor connectors on the motor board and see what results you get. If the dec motor runs, but the RA motor is now inop, then the problem is with the board. If the Dec motor still doesn't run the problem is with the Dec motor or connections.

A very quick check before you dive into tearing stuff down would be to power on the mount, and before aligning or doing anything, command the RA for short slews east and west, then try commanding the DEC north and south the same way. Is it dead silent on the DEC motor, or does it make any sound?

If it's dead silent, the procedure in Stan's post above is what you're doing.

If it clicks or bumps or grunts, but doesn't turn, then check the leads to the motor and make sure no debris is in the gears. Or it may be the motor has died. As a last resort you can try pulling the motor out of the drive train and make see if it and the worm function normally apart.

If the motor runs at full speed but the axis doesn't move, look for a loose gear set screw. If the mount had this problem its accuracy in GOTO should have mysteriously dropped off shortly before the failure.

I'm having the exact same issue with my CG5. Waiting for parts to arrive.

In my case I know the DEC motor is good so now I just need to isolate the issue. Could be the DEC board but I don't think so. (Recently replaced) Could be the main power board (which is only $20). Could be the motor board as well but I don't think it is since that has already been replaced also.

Well, here's a bit of an update. I got home very late from the star party last night and was too tired to unload all my gear out of the car. We had to go to my nephew's birthday party today. I figured I'd just leave my scope gear in the car and see about setting it up at the party for some solar. My nephew likes space stuff and was very excited when I offered to set it up.

Of course, I was fully expecting the DEC axis to be inoperable again. So I planned to just align the sun as best as I could and let the RA motor handle the tracking. Lo and behold, the DEC axis was working after setting it up. So, I'm very happy that it's not dead.

However, I am still concerned that there may be a growing problem. I've had several instances in the past couple months where my GoTo mount has just stopped working in one axis or another. If this continues to happen, I will definitely keep a log of which axis is acting up and the circumstances surrounding it.

To answer rdandrea's question, I received no error on the hand controller. The DEC axis just wouldn't move. I could not hear whether the motor was still running or not as there were many people talking around me. The hand controller continued to display the spinner indicating that it was still trying to slew, but it wasn't moving anywhere.

As Rod pointed out, the DEC cable may be to blame. However, considering your extensive use recently, there is another possibility. The cables inside the RA motor housing run near and sometimes directly on top of the RA motor. With a lot of use the motor heats up and can burn the sheilding on the cables if they lie directly on the motor. I have seen this any number of times and the results can range from a dead axis to wild slewing. I would suspect that the cable that connects the motor board to the socket for the DEC cable is lying directly on the RA motor and is getting melted and may be completely through the shielding at this point. That can cause a short (sometime intermittent) that will cause the problems you are seeing.

If you do not see and obvious problem with the DEC cable, then you should remove the RA motor housing and take a look at the cables. If the cable is damaged, but not too bad, then some electrical tape will take care of the problem.

Rod, I verified I had the DEC cable in the correct port. Also, this particular DEC is relatively new. I was having some issues with the original DEC cable I got with the scope and replaced it last year. However, that does not mean the new one isn't going bad somehow, too.

Ed, I will definitely take the casing apart and check on the wires inside to be on the safe side. The DEC axis seems to be working fine again now. It operated flawlessly for several hours yesterday in the blazing sun as I had the scope set up for solar observing at my nephew's birthday party. So, it definitely seems like an intermittent issue, but I want to take care of it before it gets worse. BTW, thanks for a great product. I purchased the DIY Hypertune kit a year and a half ago and tuned up my mount real good. Works great now; nice and smooth with no more backlash!

I have had this happen twice on my AS-GT in 4 years of ownership - I carefully took both motor casings apart, made sure the internal plugs were seated correctly, put it back together, and it worked great.

Bugger! It happened to me again last night at a star party I was hosting in my neighborhood. The N/S buttons on my hand control wouldn't work, and the scope wouldn't slew in the DEC axis when selecting an object from a list. From the get-go this time. Last time, I was halfway through the evening before it went out on me. Last night, it didn't work at all.

I was able to manually point my scope and then engage the clutch on the RA access to keep it tracking. So the evening wasn't shot by any means. Just took a little longer and a little more fussin' to get things centered. Thank the stars for GLPs and finder scopes!

I'm definitely going to have to try and find time this weekend to take the casing off the DEC housing and see what's going on in there. I really hope it is an easy fix.

I had this happen on a Vixen GP mount. In my case it was the wire to the Dec motor had pulled out from the plug. Apparently I got the mount turned too far around the axis and the wires were getting tighter every time I slewed it. Eventually they pulled away from the contacts inside the plug. I re-routed the wires, reconnected the wires to the plug and all is fine.

Well, I need to go back to the drawing board. I was out at another public outreach event last night. My mount was working fine for a couple hours. Then the DEC motor stopped working again.

I thought I had it licked this time. A week or two ago, I had taken the housing off the DEC motor and checked to make sure all wires were okay. Everything seemed to be in good order. Lots of testing after that with the mount only didn't turn up any problems.

Now that I've gone back and re-read some of the suggestions here, I see that Ed recommended opening up the RA housing (not the DEC housing) to check that the wires from the motor board to the DEC connector are okay. I'll have to try that next. Also, I'm wondering if I should just go ahead and get a new DEC cable to be on the safe side. Another thought is whether it's possible the hand control could be having some type of problem that may cause this?

Unlikely it's the HC at all. If the HC can no longer talk to one of the motor controllers you'll get an No Response 16 or 17 error message. Just stopping is usually a cabling or problem with the motor itself.

I'd follow Ed's suggestions very closely, he probably has more experience working with the internals of the CG-5 than all the rest of us on this thread combined.

Pulled off the housing on both motors tonight. Inspected all wires and fittings. Could not find any evidence of the wires melting through or shorting. I had my battery pack hooked up and the mount powered up as I VERY carefully poked around. I kept testing the DEC controls on the HC to see if anything I did made a difference.

Once I pulled the DEC housing off, the DEC motor started working again. I'm thinking that maybe the wire connection on the back of the DEC socket jiggled loose somehow. I can't be sure as I don't remembered exactly what I did just prior to the DEC motor working again. Could have been a couple different things.

In any event, I grabbed a roll of electrical tape and taped down all the wire connections on the boards and sockets just to make sure that stay nice and secure. I sat in my kitchen/"workshop" and put the mount through its paces without the OTA or any counterweights. It works perfectly fine now. I won't know for sure if I finally fixed my problem until I get out in the field with my setup again for a few hours at a time. I really hope I got it taken care of this time.

Just wanted to share my experience as well. My dec motor stopped working a few weeks ago. I have found this thread and was following it with interest for eventual solution. Since the issue became clear a few days ago, I thought I should share my experience so it might help other CN members.

The reason for the issue with my (almost) brand new CG-5 dec motor was a loose connection in the RA casing, right behind the Dec port on the board. Note that it was not the connection of the Dec port to the board, but rather the connection of the cable to the board, behind the dec port. A little playing around and my dec motor works normally now. Note that visually there was absolutely nothing wrong, I just had to move the connector to the sides a few times before my mount started working again.

I guess the issue might re-occur, but I will think of a permanent solution if it comes to that.

Hope this helps, in case anyone stumbles on the same problem (God forbid).

Grrr!!! Back to square one! I got my first chance to get out in the field with my scope after taking the mount apart a couple weeks ago. I thought I had fixed it then as I got the DEC motor to work just fine.

Tonight, I was volunteering at an outreach event/Perseids Meteor Shower Party. My DEC motor wouldn't work at all from the moment I powered up the mount. I have no idea where to go from here. Which part I should fiddle with, fix, or try to replace. From all accounts that I have read in my research on this problem, it could be anything from the DEC cable to the Power Board to the Motor Board to the wires rubbing on the housing to the DEC motor itself.

So, which part(s) do I start trying to replace first? I guess I'll start off with the cheapest ones and work my way up from there. I'll get the DEC cable, DEC board, and Power Board first. If those don't fix the problem, then I guess it's on to the more expensive items on the list. Let's see what happens. Keeping my fingers crossed!

Swapping the connectors for the motors on the MC board will test the MC board and DEC motor. If after swapping the connectors, and the DEC motor still does not work, it is not the MC board. (You will have to push the appropriate direction buttons) If the RA motor does not work, and the DEC motor now works, then the MC board is at fault.

Thanks, Stan. That makes sense. My only problem with that is that whenever I take the housings off the motors, I'm always able to get the DEC motor working again. I don't know if it is just jiggling the wires/connectors around that makes it start working again or what?!?! Then I'll put the mount all back together and test it some more. The DEC motor continues to work and everything seems hunky dory. That is until the next time I actually take my scope out into the field. Then the DEC motor stops working for me again. In the past, it would operate properly for about an hour or so before it stopped working. Now, it just doesn't work from the get-go. I have no idea what to make of the situation.

The couple of times I've had the mount inside to take off the covers and inspect everything, I did not have my OTA on the mount. I just had the mount on the tripod while working on it. So, I don't know if it is the DEC motor really starting to go out and it is able to work fine with no load on it. And then once I put the OTA and counterweights on, it is too much for the the DEC motor. Or maybe there is something else loose somewhere, and packing up my mount and transporting it knocks that connection loose every time. I don't know. So, I am going to start by replacing the cheaper parts inside and then test it out under full load. If the DEC motor still cr@ps out on me, then I know it is either the motor itself or the Motor Board. At that point, I will perform your test to see if it is the motor or the board. We'll see!

UPS says replacement parts should be delivered this coming Tuesday. So, now my question is: does ordering mundane, internal repair parts invoke the astronomy curse? I would hope not. It's not like this is some new EP or other astro toy that I'm really excited to get. I'm just trying to fix my broken mount!

I had an intermitent problem with my CG5ASGT. it finally went all out and stopped working completely (the dec).turned out to be a broken wire. the wire was broken on the inside, but no damage to the insulation. I found it by stretching the wires.

UPS says replacement parts should be delivered this coming Tuesday. So, now my question is: does ordering mundane, internal repair parts invoke the astronomy curse? I would hope not. It's not like this is some new EP or other astro toy that I'm really excited to get. I'm just trying to fix my broken mount!